Riverside County California Gold Production
By A. H. KOSCHMANN and M. H. BERGENDAHL - USGS 1968
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The geology of the mining districts has not been published, but the generalization can be made that most of the gold occurs in quartz veins that occupy fissures in granitic rocks or in country rock near granodiorite bodies (Nolan, 1936b, p. 43-45).
PINACATE DISTRICT
The Pinacate district, in Tps. 4 and 5 S., R. 4 W., a few miles west and southwest of Perris, produced a total of about 104,000 ounces of gold through 1959, all from lodes. The principal mine in this district is the Good Hope mine, originally worked by Mexicans at an unknown date; the property is credited with a production of about $2 million in gold before 1896 (Tucker and Sampson, 1945, p. 133). The district declined until the mid-1930's at which time attempts were made to rehabilitate the Good Hope and several other mines, but these efforts were largely unsuccessful. During 1943-59 only 3 ounces of gold was produced from the district.
The predominant country rock in the district is granodiorite of undetermined age (Tucker and Sampson, 1945, p. 133, 135, 138-139). Quartz veins, containing free gold and minor sulfides, cut the granodiorite.
PINON-DALE DISTRICT
The Pinon-Dale district, a large area along the north boundary of Riverside County, includes Tps. 2 and 3 S., Rs. 10 to 12 E.
The country rock of the district consists of granite, schist, and quartzite (Tucker and Sampson, 1945, p. 130-132). The gold occurs in quartz veins, most of which are in the granite.